Ultimate team ban

Yesterday evening, while searching for the Le Mans player Larouci for a FUT Gallery objective, I noticed his price was high for a silver card; I bought the card cheaply and resold it at a high price multiple times. Later, when the card's price dropped back to normal levels, I was left with excess inventory and listed them at a low price. One or two hours later, I received a notification that my account had been hit with a transfer ban. All I had done was sell a cheap silver card at a high price, and every transaction took place within the game or on the Web App—without the use of any external applications. When I appealed the decision, the only response I received was that the account had been used for coin transferring, without any specific reason being cited.